Recombination that occurs during meiosis is essential for genetic diversity, species fitness, and evolution. Here the shuffling of chromosomes does not occur at random but rather at distinct "hotspots" in eukaryotic genomes. The anatomy and control of recombination hotspots is poorly understood, especially in higher eukaryotes, as very few have been characterized in detail due to difficulties in mapping these sites. Historically the field has relied on time-consuming and expensive human population studies (the HapMap project) or extensive recombinant inbred mapping in mice. In this R21 application we seek to develop rapid, robust and cost effective methods to generate genome-wide maps of recombination hotspots in higher eukaryotes. Studies in lower eukaryotes such as yeast have revealed that following Spo11 initiated DSB, a precise cascade of events occur. Using this strong foundation together with our unique expertise in purifying meiotic cells by FACS combined with chromatin immuno-precipitation (ChIP), we are aiming to generate DSB "recombinome" atlases in mice by targeting DNA bound to the Dmc1 protein, which directs strand invasion immediately following DSB formation. The mapping of bona fide hotspots will be validated for some of the new hotspots identified by crossover analyses of recombinant inbred strains as well as by other groups on other chromosomes. Collectively, the proposed studies will validate innovative approaches for genome-wide mapping of recombination hotspots, which then can be applied by the field to interrogate their anatomy and control. Further, we believe the methods developed herein can be rapidly applied to map recombination hotspots across strains and species, including humans, and that this knowledge will lay the foundation for understanding the roles of meiotic recombination in directing genetic diversity and genome evolution. PUBLIC HEALTH RELEVANCE: The reshuffling of chromosomes during meiosis ensures genetic diversity of gametes for sexual reproduction at each generation. This reshuffling is not random but rather occurs at very specific regions coined recombination hotspots, which only represent a small fraction (1-2%) of the whole genome. The anatomy and control of recombination hotspots in higher eukaryotes is poorly understood, and this reflects difficulties in identifying hotspots, which to date has relied on large human population studies (the HapMap project) or extensive breeding and low-resolution mapping studies in the mouse. The proposed research seeks funding to rapidly generate high-resolution genome-wide atlases of recombination hotspots by obtaining DNA bound to the DMC1 protein which directs strand invasion during the initial steps of recombination. The research proposed in this R21 will provide fundamental knowledge regarding the roles of meiotic recombination in directing genetic diversity and in driving evolution.